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Effect of dietary oil supplementation on fatty acid profile of backfat and intramuscular fat in finishing pigs

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Effect of dietary oil supplementation

on fatty acid profile of backfat and

intramuscular fat in finishing pigs

Gianni Battacone, Anna Nudda, Maria Grazia Manca,

Roberto Rubattu, Giuseppe Pulina

Dipartimento di Scienze Zootecniche, Università di Sassari, Italy

Corresponding author: Gianni Battacone. Dipartimento di Scienze Zootecniche. Facoltà di Agraria, Univer-sità di Sassari. Via E. De Nicola 9, 07100 Sassari, Italy - Tel. +39 079 229371 - Fax: +39 079 229302 - Email: battacon@uniss.it

AbstrAct - Two groups of finishing gilts were fed, for 4 weeks, a commercial feed enriched

(2%) with either rapeseed oil or sunflower oil. Pig growth was monitored bi-weekly and the fatty acid composition of backfat and Longissimus muscle was determined after slaughtering. Type of dietary oil affected significantly the fatty acid profile of pork fat, especially the C18:3n-3 concentration which was higher in pigs fed rapeseed oil than in those fed sunflower oil. The content of monounsaturated fatty acids (MUFA) of Longissimus muscle was significantly higher than that of backfat, due to the its higher concentration of C18:1cis9 and C16:1. Differently, the long-chain n-3 polyunsaturated fatty acids (PUFA) content was higher in backfat than in Longissimus muscle. These results confirm that it is possible to manipulate the fatty acid composition of the diet, in order to improve the health proper-ties of the adipose tissues of pork meat.

Key words: Swine, Rapeseed oil, Sunflower oil, Fatty acid composition.

Introduction - Pork meat and products are one of the main sources of saturated fatty acids (SFA)

in the human diet. The SFA have been related to various cancers and coronary heart diseases, whereas long-chain n-3 polyunsaturated fatty acids (PUFA), which have a wide range of biological effects, are believed to be beneficial to human health (Givens, 2005). Current pig production in intensive systems has provided pork meat at a reasonable price and quality for consumers. In swine carcass, fat is de-posited in different anatomical locations, such as visceral, subcutaneous, and intramuscular (within muscle). In addition, the fatty acid composition differed between the anatomical locations of adipose tissues in pig’s carcass, especially for the monounsaturated fatty acids (MUFA) and SFA concentra-tions (Monziols et al., 2007). It is generally accepted that the fatty acid composition of pork meat de-pends on the composition of the dietary fat, the duration of the feeding treatment (Cava et al., 1997), the genetic type and the live weight at slaughter (Lo Fiego et al., 2005; Kouba and Bonneau, 2009). In finishing pigs, adding fat to the diet has the advantage of increasing the caloric content of diet and improving the production efficiency. In many cases, pig diets are supplemented with vegetable oils con-taining a high percentage of unsaturated fatty acids, favoring the production of healthy pork meat for consumers. The rapeseed oil is rich in 18 carbon fatty acids such as C18:1cis9, C18:2n-6 and C18:3n-3, which represent about 60, 20 and 10% of its fatty acids, respectively. Differently, the sunflower oil is rich in C18:1cis9 and C18:2n-6 (30 and 50% of fatty acids, respectively) as well, but has only traces of C18:3n-3 (about 1%).

An experiment was carried out with the aim to study the fatty acid profile in the backfat and in-tramuscular (Longissimus muscle) fat from carcasses of pigs fed diets enriched with 2% of rapeseed or sunflower oils.

Ital.J.anIm.ScI. vol. 8 (Suppl. 2), 477-479, 2009

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478

proc. 18th nat. congr. aSpa, palermo, Italy

Material and methods - Twenty gilts of the Landrace x Large White crossbred were fed a

com-mercial diet before the beginning of the experiment. Then, the pigs, weighing 96.3±1.1 kg (mean + s.d.), were allotted to one of two treatments on the basis of body weight and were kept in pens (5 animals/pen). The two experimental diets were obtained by adding either rapeseed oil (RSO) or sun-flower oil (SFO) to the commercial feed (at 2%). Each group (five animals) was fed 12.5 kg/d of feed throughout the experiment which lasted 4 weeks. The pigs were weighed bi-weekly. At the end of the experiment the pigs were slaughtered, after an overnight fast and electronarcosis. Subsequently, for fatty acid analysis a 7–10 cm carcass section, including the last rib with its Longissimus muscle and backfat portion, was removed from the left half-carcass of each pig. Samples of Longisimus muscle and backfat of each carcass were lyophilized and finely ground in a food processor. Fat extraction was performed according to the method described by Nudda et al. (2008), using chloroform:methanol (2:1). Fatty acid methyl esters (FAME) from the triglyceride fraction were prepared by esterification using sodium methoxide in methanol. The chromatographic conditions were the same as those de-scribed by Nudda et al. (2008). The fatty acids were identified by comparing retention times of peaks with those of methyl ester standards. The content of each FAME was expressed as a percentage of total FAME.

Analyses of variance were performed on fatty acid composition data using the general linear model procedures of SAS. The model included the effects of tissue, dietary enriching oil and their interactions.

results and conclusions - Type of dietary oil did not affect significantly (P>0.05) the final

body weight (111.9 and 114.4 kg for RSO and SFO, respectively) and the mean average daily gain (0.657 and 0.668 kg/d for RSO and SFO, respectively) of the pigs. This demonstrates that the ex-perimental diets did not differ for nutritional value. The oil x tissue interactions were not signifi-cant (P>0.05) for any variables, indicating that the oil added in the diet did not influence the fatty acid profile associated with different tissues. The mean fatty acid profiles of backfat and Longis-simus muscle fat of the two experimental groups are reported in Table 1. The results showed that the type of oil added to the diet significantly (P<0.05) affected the fatty acid profile of the pig meat. In particular, the tissues of RSO supplemented pigs have a higher percentage of C18:3n-3 and a lower n6/n3 ratio than those fed SFO. This effect could be due to the relevant presence of C18:3n-3 in rapeseed oil. Differently, the fat of pigs fed SFO had a higher content of C14:0, C16:0 and C16:1. These results agree with data of another experiment in which finishing pigs were fed different dietary fat (Mitchaothai et al., 2007). The CLAc9,t11 content was not affected by the dietary oil and the values observed in this trial were in agreement with those reported in other experiments in which the CLA was not added in the diet (Martin et al., 2008).

The fatty acid compositions differed between the anatomical locations of adipose tissues analyzed, in particular for the MUFA and PUFA concentrations, whereas no differences were observed for the SFA. The content of MUFA was significantly higher in Longissimus muscle than in backfat, due to its higher concentration of C18:1cis9 and C16:1. This result did not agree with the data reported in an experiment carried out with pigs from seven different groups of genotype and sex (Monziols et al., 2007). The CLAc9,t11 concentration was significantly higher (P<0.05) in backfat than Longissimus muscle. The PUFA content was higher in backfat than in Longissimus muscle, in accordance with the results of Monziols et al. (2007).

In conclusion, the fatty acid profile of adipose finishing pig tissue was significantly affected by the fatty acid composition of the diets administered during the last four weeks before slaughter-ing. The present experiment confirmed that the various adipose tissues of pig differ for their fatty composition. The backfat tissue had a higher concentration of PUFA and a lower content of MUFA than the intramuscular fat of Longissimus muscle. Our data demonstrate that it is possible to ma-nipulate the fatty acid composition of diet in order to improve the health properties of the adipose tissues of pork meat.

Ital.J.anIm.ScI. vol. 8 (Suppl. 2), 477-479, 2009

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479 proc. 18th nat. congr. aSpa, palermo, Italy

references - cava, R., Ruiz, J., López-Bote, C., Martín, L., García, C., Ventanas, J., Antequera, T.,

1997. Influence of finishing diet on fatty acid profiles of intramuscular lipids. triglycerides and phospholipidsInfluence of finishing diet on fatty acid profiles of intramuscular lipids. triglycerides and phospholipids in muscles of the Iberian pig. Meat Sci. 45:263-270. Givens, D. I., 2005. The role of animal nutrition in im-proving the nutritive value of animal-derived foods in relation to chronic disease. Proc. Nutr. Soc. 64:395–402.

Kouba, M., Bonneau, M., 2009. Compared development of intermuscular and subcutaneous fat in carcass

and primal cuts of growing pigs from 30 to 140 kg body weight. Meat Sci. 81:270-274. Lo fiego, D.P., Santoro, P., Macchioni, P., De Leonibus, E., 2005. Influence of genetic type, live weight at slaughter and carcass fatness on fatty acid composition of subcutaneous adipose tissue of raw ham in the heavy pig. Meat Sci. 69:107-114.Meat Sci. 69:107-114.

Martin, D., Muriel, E., Gonzalez, E., Viguera, J., Ruiz, J., 2008. Effect of dietary conjugated linoleic acid andEffect of dietary conjugated linoleic acid and monounsaturated fatty acids on productive, carcass and meat quality traits of pigs. Livest. Sci. 117:155-164.

Mitchaothai, J., Yuangklang, C., Wittayakun, S., Vasupen, K., Wongsutthavas, S., Srenanul, P., Hovenier, R.,

Everts, H., Beynen, A.C., 2007. Effect of dietary fat type on meat quality and fatty acid composition of various tissues in growing–finishing swine. Meat Sci., 76:95-101. Monziols, M., Bonneau, M., Davenel, A., Kouba, M., 2007., Comparison of the lipid content and fatty acid composition of intermuscular and subcutaneous adipose tissues in pig carcasses. Meat Sci. 76:54–60. nudda, A., Palmquist, D.L., Battacone, G., Fancellu, S., Rassu, S.P.G., Pulina, G., 2008. Relationships between the contents of vaccenic acid. CLA and n−3 fatty acids of goat milk and the muscle of their suckling kids. Livest. Sci. 118:195-203.

Table 1. Fatty acid composition of backfat and Longissimus muscle of finishing

pigs fed diet added with 2% of rapeseed oil (RSO) or sunflower oil (SFO) for the last 4 weeks.

oil tissue SEM P

Fatty acid, g/100 g FAME RSO SFO backfat muscle oil tissue

C14:0 1.07 1.20 1.13 1.14 0.026 ** ns C16:0 21.73 22.50 21.91 22.31 0.264 * ns C16:1 1.88 2.20 1.73 2.36 0.093 * ** C18:0 13.15 13.10 13.28 12.97 0.261 ns ns C18:1cis9 37.84 37.79 35.50 40.13 0.514 ns ** C18:2n-6 16.95 15.93 19.31 13.57 0.602 ns ** C18:3n-3 1.15 0.96 1.28 0.82 0.045 ** ** CLA c9,t11 0.11 0.10 0.12 0.09 0.007 ns * C20:4n-6 0.43 0.38 0.30 0.52 0.024 ns ** SFA1 36.53 37.34 36.89 36.98 0.421 ns ns MUFA2 44.81 45.29 42.11 48.00 0.650 ns ** PUFA3 18.66 17.36 21.00 15.02 0.643 ns ** MUFA/SFA 1.23 1.22 1.14 1.30 0.026 ns ** PUFA/SFA 0.51 0.47 0.57 0.41 0.020 ns ** n6/n3 13.97 15.87 14.47 15.37 0.439 ** ns

1SFA, total amount of saturated fatty acids��; 2MUFA, total amount of monounsaturated fatty acids. 3PUFA, total

amount of polyunsaturated fatty acids. ns=P>0.05; *=P<0.05; **=P<0.01.

Ital.J.anIm.ScI. vol. 8 (Suppl. 2), 477-479, 2009

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